Bluetooth: hci_sync: Check the correct flag before starting a scan

Commit Message

Jonas Dreßler Jan. 2, 2024, 6:08 p.m. UTC

There's a very confusing mistake in the code starting a HCI inquiry: We're
calling hci_dev_test_flag() to test for HCI_INQUIRY, but hci_dev_test_flag()
checks hdev->dev_flags instead of hdev->flags. HCI_INQUIRY is a bit that's
set on hdev->flags, not on hdev->dev_flags though.

HCI_INQUIRY equals the integer 7, and in hdev->dev_flags, 7 means
HCI_BONDABLE, so we were actually checking for HCI_BONDABLE here.

The mistake is only present in the synchronous code for starting an inquiry,
not in the async one. Also devices are typically bondable while doing an
inquiry, so that might be the reason why nobody noticed it so far.

Signed-off-by: Jonas Dreßler <[e-mail]>
---
 net/bluetooth/hci_sync.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

[e-mail] Jan. 2, 2024, 6:35 p.m. UTC | #1

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Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=813894

---Test result---

Test Summary:
CheckPatch                    FAIL      1.06 seconds
GitLint                       PASS      0.31 seconds
SubjectPrefix                 PASS      0.12 seconds
BuildKernel                   PASS      27.86 seconds
CheckAllWarning               PASS      30.62 seconds
CheckSparse                   PASS      36.10 seconds
CheckSmatch                   PASS      99.51 seconds
BuildKernel32                 PASS      27.13 seconds
TestRunnerSetup               PASS      435.46 seconds
TestRunner_l2cap-tester       PASS      22.92 seconds
TestRunner_iso-tester         PASS      45.88 seconds
TestRunner_bnep-tester        PASS      6.82 seconds
TestRunner_mgmt-tester        PASS      163.22 seconds
TestRunner_rfcomm-tester      PASS      10.99 seconds
TestRunner_sco-tester         PASS      14.45 seconds
TestRunner_ioctl-tester       PASS      12.15 seconds
TestRunner_mesh-tester        PASS      8.76 seconds
TestRunner_smp-tester         PASS      10.26 seconds
TestRunner_userchan-tester    PASS      7.34 seconds
IncrementalBuild              PASS      26.22 seconds

Details
##############################
Test: CheckPatch - FAIL
Desc: Run checkpatch.pl script
Output:
Bluetooth: hci_sync: Check the correct flag before starting a scan
WARNING: Prefer a maximum 75 chars per line (possible unwrapped commit description?)
#44: 
calling hci_dev_test_flag() to test for HCI_INQUIRY, but hci_dev_test_flag()

total: 0 errors, 1 warnings, 0 checks, 8 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

/github/workspace/src/src/13509236.patch has style problems, please review.

NOTE: Ignored message types: UNKNOWN_COMMIT_ID

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.




---
Regards,
Linux Bluetooth

Simon Horman Jan. 4, 2024, 5:41 p.m. UTC | #2

On Tue, Jan 02, 2024 at 07:08:08PM +0100, Jonas Dreßler wrote:
> There's a very confusing mistake in the code starting a HCI inquiry: We're
> calling hci_dev_test_flag() to test for HCI_INQUIRY, but hci_dev_test_flag()
> checks hdev->dev_flags instead of hdev->flags. HCI_INQUIRY is a bit that's
> set on hdev->flags, not on hdev->dev_flags though.
> 
> HCI_INQUIRY equals the integer 7, and in hdev->dev_flags, 7 means
> HCI_BONDABLE, so we were actually checking for HCI_BONDABLE here.
> 
> The mistake is only present in the synchronous code for starting an inquiry,
> not in the async one. Also devices are typically bondable while doing an
> inquiry, so that might be the reason why nobody noticed it so far.
> 
> Signed-off-by: Jonas Dreßler <[e-mail]>

FWIIW, I agree with this analysis and the proposed fix looks
correct to me.

Reviewed-by: Simon Horman <[e-mail]>

I do wonder if it is appropriate to treat this as a bug fix -
is there a use-visible problem? If so, the following seems appropriate to
me.

Fixes: abfeea476c68 ("Bluetooth: hci_sync: Convert MGMT_OP_START_DISCOVERY")

...

[e-mail] Jan. 4, 2024, 10:20 p.m. UTC | #3

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <[e-mail]>:

On Tue,  2 Jan 2024 19:08:08 +0100 you wrote:
> There's a very confusing mistake in the code starting a HCI inquiry: We're
> calling hci_dev_test_flag() to test for HCI_INQUIRY, but hci_dev_test_flag()
> checks hdev->dev_flags instead of hdev->flags. HCI_INQUIRY is a bit that's
> set on hdev->flags, not on hdev->dev_flags though.
> 
> HCI_INQUIRY equals the integer 7, and in hdev->dev_flags, 7 means
> HCI_BONDABLE, so we were actually checking for HCI_BONDABLE here.
> 
> [...]

Here is the summary with links:
  - Bluetooth: hci_sync: Check the correct flag before starting a scan
    https://git.kernel.org/bluetooth/bluetooth-next/c/626cef40faf0

You are awesome, thank you!

Patch

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index c920de0a2..4a5949a0e 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5554,7 +5554,7 @@  static int hci_inquiry_sync(struct hci_dev *hdev, u8 length)
 
 	bt_dev_dbg(hdev, "");
 
-	if (hci_dev_test_flag(hdev, HCI_INQUIRY))
+	if (test_bit(HCI_INQUIRY, &hdev->flags))
 		return 0;
 
 	hci_dev_lock(hdev);